In semi-active laser (SAL) sensor and similar optical sensor systems, optical energy in the light from a distant source is collected by a condenser lens system that converges the energy in the direction of a detector array. For laser light entering the optical sensor system at its limit of its field of view a portion of the optical energy from the laser light may fall outside of the active area of the detector, resulting in an ambiguity of the angle of incidence reported by the sensor.